1. Field
The present disclosure is generally related to choosing a billing structure based on an amount of color in a document, and, in particular, to a system and method for determining a billing structure for outputting documents based on processing image data in device independent space.
2. Description of Related Art
Image data comprises a number of pixels having a number of components that contribute to defining the image, such as color and intensity. The image data generally includes various color or gray levels, which contribute to the intensity of each pixel in the image. Each pixel of the image is assigned a number representing the amount of light or gray level for that space at that particular spot; i.e., the shade of gray in the pixel. Binary image data has two possible values for each pixel, black (represented by the number “1”) or white (represented by the number “0”). Images that have a large range of shades are referred to as grayscale images. For example, grayscale images have an 8-bit value (or higher) per pixel comprising 256 tones or shades of gray for each pixel in the image (gray level of 0 to 255). Grayscale image data may also be referred to as continuous tone or contone image data. The pixels in a color image may be defined in terms of a color space, typically with three values, such as RGB—R for red, G for green, and B for blue—or four values, such as CMYK—C for cyan, M for magenta, Y for yellow, and K for black, or composite black.
The pixels may also be defined in terms of device independent space (e.g., when inputting image data, such as standard RBG (sRGB) or CIE L*a*b) or a device dependent space (e.g., when outputting image data, such as RGB or CMYK). When outputting image data to an output device (e.g., copier, printer, or multi-function device (MFD)), a percentage scale may be used to identify how much ink is employed for a print job. Such information may typically be used for billing a customer for print jobs. For example, some methods employ a billing strategy based on an estimated amount of ink or toner consumption; others bill customers based on a print mode selection (e.g., draft, standard, color, enhanced, etc.) of the output device. In dynamic print-job environments, because printing documents using black ink or toner is less expensive than using colored ink or toner, billing is often based on the amount of color content contained in the job to be printed. In order to bill customers for color printing, color detection is an important feature required in image path. Color detection is used to analyze documents for presence of color as well as an amount of color in order to bill customers accordingly. Generally, the higher the presence and amount of color in a document, the higher the cost.
Some systems include counting the number of pixels in the image data of the document to be printed. For example, a number of binary pixels associated with the CMYK color planes may be counted at the time of marking for output in the image path. Generally, however, with existing color detection and counting methods, a pixel will be labeled as color when the presence of any one of the C, M, and Y signals is detected. In solid ink and ink jet products, black pixels are typically rendered as composite black (using a CMYK plane or scale) in order to achieve a better output quality. When pixel counting is performed in the image path before marking, then, a page or document with composite black or grayscale image data will be classified as color. Such a classification may cause a higher color billing strategy or a higher billing tier to be selected, and therefore the customer may be billed for printing the document at a higher rate even if the document does not have a significant amount of color pixels. This is not generally acceptable from a customer point of view. Alternatively, fixing the price of print jobs irrespective of the content of the image is not acceptable from a supplier's point of view.
Accordingly, an improved system and method of estimating the amount of color content in a document and correctly billing customers is desirable.